Substrate-Dependent Activation of the Vibrio cholerae vexAB RND Efflux System Requires vexR
Fig 6
Indole activates vexRAB expression.
(A) Schematic of the V. cholerae tryptophan biosynthetic pathway. (B) The indicated C6706 strains bearing pDT1777 (vexRAB-lux) were grown in 96-well plates under AKI conditions for 5 h when luminescence (RLU) and OD600 were measured. Data are the mean +/- SEM of three independent assays. Two-way Anova with Dunnet’s post-hoc test compared to WT was used to determine significance. * = P<0.01; ** = P<0.0001. (C) V. cholerae N16961 containing pXB233 (vexRAB-lacZ) was grown with or without indole, L-tryptophan, or anthranilic acid at the indicated concentrations under AKI conditions for 5 h before vexRAB expression was determined as described in the methods. Bars indicate the mean +/- SD of three independent experiments. One-way ANOVA with Dunnet’s post-hoc test was used to determine significant changes relative to growth in media alone. * = P<0.001.